Well, I would try save a test document to one of those two Documents folder locations, then see if your newly saved document duplicates in the other folder.
Alternatively, you could just delete something from one of the locations, then see if it deletes from the other location.
You can also list all the Junctions and Symbolic Links with Junction | Sysinternals with the command: junction -s C:\
or junction -s F:\
That will tell you if F:\Music\Documents is a Symbolic Link for C:\Users\GLW\My Music\Documents .
My Computer
Computer type
PC/Desktop
OS
Windows 7 x64, Vista x64, 8.1 smartphone
CPU
Intel E8400 65W 64-bit
Motherboard
Gigabyte EP45-UD3LR
Memory
DDR2 2 x 2GB, 1GB x 2
Graphics Card(s)
XFX Radeon HD5750
Sound Card
AMD High Definition Audio; Realtek High Definition Audio